refactor: clean up verbose migration comments

Remove redundant Qt6 migration comments that restate obvious API changes:
- QtConcurrent::run parameter order explanations (preserved where lambda wrapping needed)
- QStringRef/QStringView API changes (shortened to essential info)
- QComboBox::activated signal signature change
- QMap::unite() removal semantics
- QAction include path change
- QMouseEvent/QWheelEvent position() API
- QList/QVector equivalence in Qt6
- QFuture continuation API
- Code generation comments

Preserved comments explaining non-obvious Qt6 behavior or necessary
API migration details.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

qt6-after/qt6-migrated-legatus/Lts/Proxies/Buildings/BuildingControlUnit/VWM/vwm_api.cpp

@@ -33,7 +33,7 @@ namespace VWM
 namespace
 {
 // Ensure QPoint3D meta-type is registered for queued connections
-// Qt6: Q_DECLARE_METATYPE is sufficient, no need for qRegisterMetaTypeStreamOperators
+// Q_DECLARE_METATYPE is sufficient for custom types
 static const bool point3dRegistered = []() {
     return true;
 }();